American teens lead the nation in smartphone use, with one-quarter of teens accessing the Internet mostly from their cellphones, according to the Pew Internet & American Life Project survey.

About 37 percent of teens said they owned a smartphone, a sharp increase from 23 percent in 2011, according the survey. About 25 percent of teens use their cellphones to access the Internet, compared to 15 percent of adults.

Pew said this group of "cell-mostly" Internet users portends an explosion of mobile Internet use in the future.